The Future

Some characters have ideas like time travel worked into their basic concept. It's important to keep this sort of thing in check, as it can complicate the overarching timeline to the point of invalidating it. To this end, it's going to be understood that within this fictional universe, time is decidedly causal. Each decision creates an infinite number of alternate futures, just as it also causes an equally infinite number of possible futures to cease to exist. Traveling through the timeline makes it virtually impossible to find your original starting point, as causality has virtually guaranteed it has ceased to exist. Only very specific technologies will be allowed exceptions, such as Brainiac 5's time travel technology, if only because His 12th level intellect can understand the machinations of temporal science in a way we never will. (Even so, he is limited to very specific uses of the technology to ensure the existence of his particular timeline.)